Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.31.1 (micrococcal nuclease)
 2,818 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Conformational changes in the chromatin of the brain were studied during the development of the rat (3-, 14- and 30-day old) using micrococcal nuclease (MCN) and DNase I. The rate and extent of digestion of chromatin by MCN is not altered during development. However, pre-incubation of slices of the cerebral cortex with ZnCl2 increases the initial rate of digestion by MCN by 2-3-fold, and also enhances the production of monomer DNA. The rate and extent of digestion of chromatin by DNase I is greater in an early stage of development. The initial rate of digestion by DNase I is stimulated by 3-4-fold after ZnCl2 treatment. These data show that changes occur in the conformation of chromatin, particularly in the internucleosomal region of brain cells as they pass from dividing to the non-dividing state.
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PMID:Conformational changes in the chromatin of the brain of developing rats and its modulation by zinc chloride. 670 52

Apoptosis is the predominant form of cell death observed in a variety of physiological and pathological conditions such as cancer involution, insect metamorphosis, the development of the immune and nervous systems, and embryogenesis. The typical nuclear changes taking place in apoptotic cells include extensive condensation of chromatin and internucleosomal DNA fragmentation into units of 200 base pairs. However, the mechanisms responsible for both chromatin condensation and DNA fragmentation have yet to be elucidated. In this study, micrococcal nuclease and the divalent cations, Ca2+ and Mg2+, were applied to isolated nuclei in an attempt to reconstitute in vitro the digestion of genomic DNA associated with apoptosis. Micrococcal nuclease was found to induce a typical pattern of DNA fragmentation, but did not give rise to chromatin condensation, whereas Ca2+/Mg2+ induced both chromatin condensation and DNA fragmentation in isolated mouse liver nuclei. When the endonuclease inhibitor ZnCl2 was used, the DNA fragmentation induced by Ca2+/Mg2+ in nuclei could be completely inhibited, but chromatin condensation still occurred. For comparison, intact liver cells were treated with valinomycin, a potassium ionophore, which gave rise to an atypical cell death, with chromatin condensation appearing without DNA fragmentation. Our results suggest that endonuclease activation in apoptosis is neither necessary nor sufficient to induce chromatin condensation, and that DNA fragmentation and chromatin condensation may be triggered through separate pathways during apoptosis.
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PMID:Separate metabolic pathways leading to DNA fragmentation and apoptotic chromatin condensation. 829 67